The invention relates to a method and device for adjusting an air guide system in a sheet-fed printing machine. Such air guide systems are used to convey and guide printing material, generally a sheet of paper or cardboard. Such a system includes a large number of different air-assisted elements, such as blowing or blast systems, carrying-air cushions and so forth, referred to as xe2x80x9cactuatorsxe2x80x9d in connection with this invention.
The air guide system ensures precise conveyance and guidance of the individual sheets, which are held at the leading edge thereof by grippers. In this regard, the greatest accuracy is involved, specifically, both with respect to the path guidance, i.e., the avoidance of deviations from a desired path predefined by the grippers, and also with respect to chronological sequence. Problems increase as the machine speed increases.
The universal availability of a machine for assignment both to the thinnest papers (bible printing paper) and the thickest cardboards requires, on the one hand, a large adjustment range and, on the other hand, a precise adjustment of the air parameters. In particular, this applies to the pressure at the nozzle outlet and, therewith, also the air velocity and the air volume. These air parameters are controlled by throttle valves or bypass flaps, remotely adjustable motorized valves, speed-controlled air generators, and many others. In this regard, the aforementioned parameters which are critical to sheet conveyance, hereinafter referred to as xe2x80x9cconveying parametersxe2x80x9d, are adjusted to the specific data of the respective print job.
Parameters which are sheet-specific are, in particular, the grammage, i.e., the weight of the sheet in g/m2, and the sheet format. However, other variables are also considered, for example, the stiffness of the sheet or the surface condition thereof. It is believed to be obvious that the conveying parameters have to be selected with a view to the sheet parameters in order to achieve an optimum result, i.e., trouble-free conveyance of the sheet through the entire machine. It may also happen that the parameters of a blowing or blast air nozzle, when the sheet parameters are changed, for example, from a lower to a higher grammage, must be changed at a specific location on the conveying path rather than at another location.
Parameters which are specific to printing machines are critical for the operation of the blowing or blast air nozzles. The most important printing machine-specific parameter is the production printing speed, i.e., the machine speed. Further printing machine-specific parameters are the switching on and switching off, i.e., starting and stopping, respectively, of individual printing units, the presence of particular in-line applications: varnishing, drying, measuring, cutting, and so forth.
Printing form or plate inking and moisture takeup change the printing material properties as they pass through the machine.
With regard to heretoforeknown printing machines, the air parameters of the individual air handlers, i.e., for example, blast air nozzles, respectively, are adjustable only individually. Nevertheless, it has become known heretofore to adjust groups of air handlers. In any event, whenever a new print job is performed, a great number of adjustments have to be made, with sheet-specific parameters differing from the preceding print job and/or with different printing machine-specific parameters, for example, at a higher or lower production printing speed.
From the plethora of all of the possible adjustments, the operator has to find the correct adjustment. The operator therefore has to feel his way empirically to the correct values of the conveying parameters in order to achieve a trouble-free or satisfactory conveying result. In this regard, he or she orients himself or herself, respectively, to the aforementioned physical sheet-specific and machine-specific parameters, as well as combined parameters. This requires not only a great deal of skill on the part of the operator, but is also time-consuming. The operator has to decide, from his or her understanding of the technical/physical effect or from his or her own experience, whether upward or downward corrections are necessary in order to optimize the conveying parameters, in particular the air pressure of the blast nozzles.
Previous attempts at a solution to these problems include the following:
The performance range of the machine was restricted to specific applications, in order to achieve a reduction in the adjustment operations of conveying parameters; the performance of the air generators was limited in order to avoid maladjustments; the operating points and viewing windows directly adjacent the sheet guide path were configured ergonometrically; production was performed at a reduced machine speed because, in the daily business of a print shop or printing plant, for the most part the increased changeover time was not amortized by the higher production printing speed achieved as a result.
All these attempts at finding an appropriate solution were unsatisfactory, specifically in relation to the expenditure of time, to the quality of the printed result and also to the requirements regarding the capability and experience of the operator.
The published European Patent Document EP 0 553 321 B2 describes a device for regulating and/or controlling individual actuating elements such as blast nozzles in the region of a delivery of a sheet-fed printing machine. In this regard, sheet-specific and printing machine-specific characteristic data are fed to a computer. In the case of individual actuating elements, a control device performs a format-dependent adjustment. The computer uses the characteristic data to determine the energy of the sheet oncoming in the delivery and, in addition, ensures that the control variables of the actuating elements apply precisely that amount of energy which corresponds to the energy of the oncoming sheet in the delivery region.
The published German Patent Document DE 197 14 204 A1 describes a device for regulating the blast air on a sheet feeder. In this regard, valves which control the supply of blast air are adjusted in accordance with control characteristic curves which, in turn, for its part, take the sheet properties into account.
The published German Patent Document DE 34 13 179 A1 describes a control and regulating device for a sheet delivery of a sheet-fed printing machine. In this regard, all of the required adjustments of adjustable elements of a sheet delivery are adjusted from a single location and are adapted or matched automatically to the changing conditions in accordance with a predefined or prescribed program.
None of these proposals was able to solve the problems arising here. In particular, it is impossible to take into account parameters which are not contained in the database, which leads fundamentally to maladjustments. There is a basic contrast between
It is accordingly an object of the invention to provide a method and device for adjusting an air guide system in a sheet-fed printing machine wherein the individual conveying parameters of actuators, such as blast air nozzles, can be adjusted quickly and automatically, even by less experienced personnel, for specific job data having special sheet-specific and printing machine-specific parameters (preset and adaptation), and the ability to exert a manual influence is maintained so that the advantages of full automation are usable together with those of manual control, excluding the disadvantages, so that an optimal printed result is attained in the shortest time.
With the foregoing and other objects in view, there is provided, in accordance with one aspect of the invention, a method of adjusting an air guide system having various actuators, in a sheet-fed printing machine, which comprises the following method steps: providing characteristic curves containing conveying parameters which are critical for sheet conveyance, plotted against a printing machine-specific parameter, and which are optimal for sheet-specific parameters; storing the characteristic curves in a memory; feeding the actual sheet-specific and printing machine-specific data of a print job to a CPU (central processing unit of a computer); accessing by the CPU the characteristic curve which is optimal for the actual data from the memory; and outputting the appropriate commands to the individual actuators; and, if necessary, providing operator intervention.
In accordance with another mode of the method of the invention, there is provided a method of adjusting an air guide system having blast air nozzles, in a sheet-fed printing machine, which comprises the following method steps: providing characteristic curves containing a conveying parameter of blast air pressure which is critical for sheet conveyance, plotted against the printing machine-specific parameter of the printing machine speed, and which is optimal for a sheet-specific parameter selected from the group thereof consisting of grammage and sheet format, respectively; storing the characteristic curves in a memory; feeding the actual sheet-specific and printing machine-specific data of a print job to a CPU; accessing by the CPU the characteristic curve which is optimal for the actual data from the memory; and outputting the appropriate commands to the individual actuators; and, if necessary, providing operator intervention.
In accordance with a further mode, the method includes, when accessing the optimal characteristic curves, determining at least one concrete condition selected from the group thereof consisting of a turning up of the printing material, a flapping of the printing material, a contact ghosting of the printed image, and a smearing of the printed image, respectively.
In accordance with an added mode of the invention, the method includes, as a scaling function, providing a plot diagram or graph reproducing the effects of the adjustment for various grammages and, consequently, taking the behavior of the printing material into account.
In accordance with an additional aspect of the invention, there is provided a device for regulating and/or controlling an air guide system in a sheet-fed printing machine, the air guide system having various actuators, comprising a memory stored with characteristic curves for reproducing conveying parameters, which are critical for sheet conveyance, plotted against printing machine-specific parameters, and which are optimal for sheet-specific parameters; an input device for inputting actual parameters selected from one of the groups thereof consisting of actual sheet-specific parameters and printing machine-specific parameters, respectively; and a CPU for determining optimal characteristic curves, taking the actual characteristic data into account, and for feeding the relevant parameters to a reference-value or set-point transmitter.
In accordance with a concomitant feature of the invention, there is provided a device for regulating and/or controlling an air guide system, having blast air nozzles as actuators, in a sheet-fed printing machine, comprising a memory stored with characteristic curves for reproducing blast air pressure, as a conveying parameter critical for sheet conveyance, plotted against printing machine speed, as printing machine-specific parameters, and which are optimal for sheet-specific parameters consisting of at least one of grammage and sheet format, respectively; an input device for inputting actual parameters from the groups consisting of actual sheet-specific and actual printing machine-specific parameters, respectively; and a CPU for determining optimal characteristic curves, taking the actual characteristic data into account, and for feeding the relevant parameters to a reference-value or set-point transmitter.
In the foregoing manner, the efficiency of the machine may be optimized, the changeover times may be reduced and the quality and the output capacity can be attained independently of the subjective experience of the operating personnel.
According to the basic concept of the invention, characteristic curves are provided wherein conveying parameters, such as the blast or blowing air pressure, are plotted against printing machine-specific parameters such as the production printing speed, specifically for different print jobs with the sheet-specific parameters thereof, such as the grammage of the sheet or the sheet format.
The aforementioned characteristic curves therefore contain the data for the optimal adjustment for a quite specific printing material, respectively.
Control of the air parameters is performed by evaluating the aforementioned sheet-specific and printing machine-specific parameters. This makes presetting possible. In order to adapt the machine to job-specific conditions, operator intervention in the respective data is then possible. This requires a further variable, which is referred to herein as an xe2x80x9cinfluencing variablexe2x80x9d. This produces a changed characteristic curve, which then leads to different air adjustments.
It is desirable for the preset adjustment to cover all the practical cases. This is not achieved, however, in practice. What is sought after, however, is that a high percentage be covered, for example 80%. In the remaining number of cases, the pressman must intervene and perform an appropriate adjustment.
According to the invention, when the characteristic curves for the optimal conveying parameters are being provided, a start may be made from physical xe2x80x9cabstractxe2x80x9d variables, such as from the grammage or the stiffness or the format of the sheet.
In further refinement of the invention, however, provision is made for ignoring these variables completely and, instead, for using quite concrete variables based upon results, such as casting or turning up of the printing material, contact ghosting of the printed image, smearing of the printed image, flapping or fluttering of the printing material, and others.
The pressman is able to assess these conditions or phenomena reliably. The physical background and the effective variables to be attacked by the pressman can be completely disregarded by the pressman in the process. The more extensive teaching according to the invention therefore comprises the following:
Using the aforementioned conditions or events, such as upward turning, contact ghosting, smearing, or flapping or fluttering, the characteristic behavior of the combination of physical parameters (grammage, stiffness, centrifugal force and-so forth) and conveying parameters (blasting force, quantity of air, air pressure and so forth) are systematically recorded in terms of the effect thereof in trials. The characteristic curves are then stored in such a manner that the pressman can register the results of changes as dual decisions of more (+) or less (xe2x88x92). He can therefore close the control loop in a qualified manner without any physical know-how.
These typical and characteristic variables can be used on their own or in addition to the physical variables such as grammage, stiffness and so forth. This is beneficial in the case wherein a large number of parameters act which cannot be registered and evaluated in detail.
Example: the pressman prepares proofs and, in so doing, establishes that there is contact ghosting to a specific extent at a specific location. He or she communicates this observation to the machine. An algorithm or a characteristic curve is inherent to the machine. Because of this, an appropriate correction to the relevant air system is effected thereby in the machine.
Such a procedure is primarily recommended in the case of repeat jobs, wherein job-data storage of the aforementioned type can take place.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method and device for adjusting an air guide system in a sheet-fed printing machine, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, wherein: